Method of Assembling and Packing an Automotive Airbag

ABSTRACT

A method of assembling an airbag for a seatbelt restraint such that the deflated airbag lays flat when it is stacked and secured to a webbing of the seatbelt. The airbag is assembled from a plurality of material strips. The strips are edge joint welded together so that the joints lay flat between the individual strips comprising the airbag.

BACKGROUND OF INVENTION

The present invention relates to a method of assembling an automotiveairbag and in particular to a method of assembling an automotive airbagsuch that it packs flat.

Automotive vehicles use airbag systems to protect a vehicle occupantduring collisions. The airbag is a bag that rapidly inflates during acollision to provide cushioning for the vehicle occupant. A housing fromwhich the airbag deploys may be located throughout a vehicle passengercompartment, including being incorporated into a webbing of a seatbeltrestraint.

The seatbelt webbing in automotive vehicles typically slides over aD-ring when extended and retracted. However, incorporating the airbaginto the webbing increases the thickness of the webbing and the tendencyof the webbing to bubble up or pucker. The increased thickness andtendency to bubble up or pucker makes the airbag incorporating webbingboth less aesthetically pleasing to the vehicle occupant and moredifficult to pass over the D-ring and thus more difficult to for thevehicle occupant to don and doff the seatbelt. The difficulty in passingover the D-ring may necessitate designing the seatbelt system so theairbag component does not pass over the D-ring, which then may requirethe addition of a second retractor for the lap portion of the seatbeltassembly. This makes packing the system with a vehicle more difficultand costly. Additionally, in applications where a D-Ring is notrequired, such as a sedan, a thin flexible airbag pack is still desiredto allow for the webbing with integrated airbag to be stowed on aconventional sized retractor.

SUMMARY OF INVENTION

An embodiment contemplates a method of assembling and packing an airbag.Stacking a plurality of material strips having first and second edges.Welding pairs of first edges together and pairs of second edgestogether, the pairs of second edges being staggered from the pairs offirst edges, to form an accordion stack in which the strips in the stacklay flat. Forming a tube having first and second openings by edge jointwelding together top and bottom strips of the stack. Closing the firstand second openings by edge joint welding to form an inflatable bag.Securing the bag to a seatbelt webbing.

Another embodiment contemplates a safety restraint airbag assemblycomprising an inflatable bag comprising a plurality of material stripsedge joint welded together such that, at weld joints between the strips,the strips lay flat in a stack. The bag is secured to a seatbeltwebbing.

Another embodiment contemplates a method of assembling and packing anairbag. Welding a plurality of material strips into an inflatable bagsuch that, at weld joints between the plurality of strips, a first striplays flat on top of a second strip. Stacking the strips in a stack.Securing the bag to a seatbelt webbing.

An advantage of an embodiment is that the airbag packs flat, which isadvantageous when used in the seatbelt restraint, and may also be usefulfor other vehicle airbag applications. This reduces cost and complexityof needing a second seatbelt retractor, or taking up more packagingspace then is desirable by allowing for a conventional sized seatbeltretractor. The seatbelt is also easier for the vehicle occupant to donand doff.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic elevation view of an airbag in a seatbeltrestraint.

FIG. 2 is a schematic elevation view of an airbag assembly.

FIG. 3 is a schematic perspective view of an airbag assembly.

FIG. 4 is a schematic perspective view of a packed airbag.

FIG. 5 is a schematic perspective view of an airbag assembly.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates a seatbelt airbag system 10 for anautomotive vehicle 12. The seatbelt airbag system 10 is merelyexemplary, and may take other forms, which may be a three point systemor a four point belt system. The seatbelt airbag system 10 includes aseatbelt restraint 14. The seatbelt restraint 14 may be a type known toone skilled in the art. For example, illustrated is a three-pointseatbelt restraint comprising a seatbelt webbing 16, a buckle 18, aD-ring 20, and a retractor 22. The webbing 16 is secured to vehiclestructure or a vehicle seat 26 at a first end, passes over the D-ring 20and is guided towards the retractor 22, which receives a second end ofthe webbing 16. The retractor 22 provides tension in the webbing 16 bytaking up and spooling an excess of the webbing 16. The webbing 16passes through the tongue slot 17 which attaches to the buckle 18 andholds the seatbelt restraint 14 across a vehicle occupant 24 seated inthe automotive vehicle seat 26. An airbag 28 is secured to the webbing16. For example, the airbag 28 may be secured in a sleeve 88 on theairbag 28.

FIG. 2 schematically illustrates an airbag assembly. A method ofassembling the airbag 28 for packing flat in the seatbelt airbag system10 will also be discussed relative to FIG. 2. A plurality ofintermediate strips 30 is vertically stacked between a top strip 32 anda bottom strip 34. The intermediate strips 30 each have a first andsecond edge. The intermediate strips 30, the top strip 32, and thebottom strip 34 are fabricated from airbag material known to one skilledin the art. For example, the material may be a woven nylon fabric. Avolume of the airbag 28 is a function of, in part, a quantity ofintermediate strips 30 between the top strip 32 and the bottom strip 34.The greater the quantity of the intermediate strips 30, the greater thevolume of the airbag 28. The width of each strip 30 is generallydetermined by the width of the webbing 16, which may also affect thevolume of the airbag 28. The intermediate strips 30 may all be the samesize or vary in size.

The intermediate strips 30 are welded together in accordance with a weldpattern. In the weld pattern, a first edge 38 of a first strip 36 isedge joint welded to a first edge 42 of a second strip 44. A second edge40 of the first strip 36 is edge joint welded to a second edge 46 of athird strip 48. The second strip 44 and the third strip 48 are onopposite sides of the first strip 36. Neither the first edge 38 nor thesecond edge 40 of the first strip 36 are welded to both the second strip44 and the third strip 48. The weld pattern results in the edge jointwelds of the intermediate strips 30 being staggered between the firstand second edges. The airbag 28 may be assembled by sequentiallystacking and edge joint welding adjacent strips. Alternatively, theairbag 28 may be assembled by stacking all the strips and then, afterstacking, edge joint welding the strips. In either case, the result isan accordion (bellows) shape.

Assembly of the airbag 28 uses edge joint welds. As understood by oneskilled in the art, an edge joint weld involves laying a first substrateflat on a second parallel, or nearly parallel, substrate and welding acontact area between the first and second substrates along an edge. Theedge joint weld allows the two substrates to be retained parallel andflat against each other. As used for the airbag 28, the edge joint weldpermits an upper strip to lay flat on top of a lower strip, including ata joint between the upper and lower strips. By using the edge jointweld, the intermediate strips 30 stack flat between the top strip 32 andthe bottom strip 34. In the weld pattern, the use of the edge joint weldallows the first strip 36, the second strip 44, and the third strip 48to stack flat.

The top strip 32 has a first edge 50 and a second edge 52. The bottomstrip 34 has a first edge 54 and a second edge 56. The top mostintermediate strip 30 is a top transition strip 58. The top transitionstrip 58 has a first edge 60 and a second edge 62. The first edge 60 ofthe top transition strip 58 is edge joint welded to the first edge 50 ofthe top strip 32. The second edge 62 is edge joint welded in accordancewith the weld pattern. The bottom most intermediate strip 30 is a bottomtransition strip 64. The bottom transition strip 64 has a first edge 66and a second edge 68. The first edge 66 of the bottom transition strip64 is edge joint welded to the first edge 54 of the bottom strip 34. Thesecond edge 68 is edge joint welded in accordance with the weld pattern.The second edge 52 of the top strip 32 is welded to the second edge 56of the bottom strip 34.

The intermediate strips 30, top strip 32, and bottom strip 34 have afirst face 70. The first face 70 alternates between facing upward anddownward in the intermediate strips 30. The first face 70′ of the topstrip 32 faces opposite the orientation of the first face 70 of the toptransition strip 58 and the first face 70″ of the bottom strip 34 facesopposite the orientation of the first face 70 of the bottom transitionstrip 64. This puts the first face 70 outside the volume of the airbag28 when the airbag 28 inflates. The first face 70 may be coated. Forexample, the first face 70 may be coated with a silicone coating toretain an inflation gas longer when the airbag 28 is inflated.

Fabrication of the intermediate strips 30, top strip 32, and bottomstrip 34 allows for measurement tolerances. The material strips may becut from a double layer of material. This results in paired upper andlower strips. An upper strip matches the size of its corresponding lowerstrip. When the pairs of upper and lower strips are located, an equalnumber of strips from the center of the intermediate strips 30, thesummed tolerance of the upper strips will be offset by the summedopposite tolerance of the lower strips.

In a direction perpendicular to a weld of the weld pattern, the topstrip 32 and bottom strip 34 have a greater dimension than theintermediate strips 30. This allows the second edge 52 of the top strip32 to reach the second edge 56 of the bottom strip 34 for welding.Further, first and second edges of the intermediate strips 30, top strip32, and bottom strip 34 are on non-intersecting lines. The edge jointweld may be made by any suitable welding technique known to one skilledin the art. For example, the welds may be ultrasonic.

FIG. 3 schematically illustrates the airbag 28 with all first and secondedges welded. The weld pattern assembles the intermediate strips 30 intoa Z-shaped accordion stack 80. The airbag 28 has a first end 82 and asecond end 84. The first end 82 and the second end 84 are welded closedso that the volume of the airbag 28 may be inflated.

FIG. 4 schematically illustrates a packed and uninflated airbag 28.Connected to the airbag 28 is an inflation input 86. The inflation input86 is used to deploy the airbag. The uninflated airbag 28 is secured inthe sleeve 88 (illustrated partially cutaway for clarity) of theseatbelt webbing 16.

FIG. 5 schematically illustrates an airbag 128. As FIG. 5 is a variationof the airbag illustrated in FIG. 2 and FIG. 3, like reference numeralsdesignate corresponding parts in the drawings (but with 100 serieselement numbers) and detailed description thereof will be omitted.

A top strip 132 extends beyond a top weld 190 and a bottom strip 134extends beyond a bottom weld 192. Beyond welds 190 and 192, the top andbottom strips 132 and 134, respectively, are joined by a rip stitch 194.The rip stitch 194 allows the top and bottom strips 132 and 134,respectively, to unstitch when airbag 128 inflates.

The top and bottom strips 132 and 134, respectively, contain the airbag28 without needing the sleeve 88 illustrated in FIG. 4. The top andbottom strips 132 and 134, respectively, may be fabricated from atactilely pleasing material that still allows for gas retention whenairbag 128 is inflated. Alternatively, outward faces of the top strip132 and bottom strip 134, respectively, may have a tactilely pleasingcoating or layer.

The top and bottom strips 132 and 134, respectively, are sewn at a joint196 to a seatbelt webbing 116 by a stitch 198. Alternatively, the topand bottom strips 132 and 134, respectively, may be seatbelt webbing.

While certain embodiments of the present invention have been describedin detail, those familiar with the art to which this invention relateswill recognize various alternative designs and embodiments forpracticing the invention as defined by the following claims.

What is claimed is:
 1. A method of packing an automotive airbagcomprising: stacking a plurality of material strips having first andsecond edges; edge joint welding pairs of first edges together and pairsof second edges together, the pairs of second edges being staggered fromthe pairs of first edges, to form an accordion stack in which the stripsin the stack lay flat; forming a tube having first and second openingsby edge joint welding together top and bottom strips of the stack;closing the first and second openings by edge joint welding to form aninflatable bag; and securing the bag to a seatbelt webbing.
 2. Themethod of claim 1 wherein the strips have first and second faces and thestrips are arranged such that the first faces are outside the bag whenthe bag is inflated.
 3. The method of claim 2 wherein the first face iscoated.
 4. The method of claim 1 wherein the strips have a first faceand the strips are stacked vertically with the first face alternatingbetween facing a first direction and a second opposite direction.
 5. Themethod of claim 1 comprising a first step in which the strips are cutfrom a double layer of material to form a plurality of paired upper andlower strips, the upper strip matching in size to the lower strip, andthe upper and lower strips arranged so that an upper strip and amatching lower strip are an equal number of strips from a center of thestack.
 6. The method of claim 1 wherein, in a direction perpendicular toa line between the first and second openings, the top and bottom stripshave a greater dimension than the remaining plurality of strips.
 7. Themethod of claim 1 wherein the welds forming the stack are onnon-intersecting lines.
 8. The method of claim 1 wherein the material iswoven nylon fabric.
 9. The method of claim 1 wherein the welding isultrasonic.
 10. The method of claim 1 wherein the seatbelt webbing isused in a three-point vehicle occupant seatbelt.
 11. An automotivesafety restraint airbag assembly comprising: an inflatable bagcomprising a plurality of material strips edge joint welded togethersuch that, at weld joints between the strips, the strips lay flat in astack; and a seatbelt webbing, the bag being secured to the webbing. 12.The assembly of claim 11 wherein the strips have first and second facesand the strips are arranged such that the first faces are outside thebag when the bag is inflated.
 13. The assembly of claim 12 wherein thefirst face is coated.
 14. The assembly of claim 11 wherein the materialstrips are woven nylon fabric
 15. The assembly of claim 11 wherein thestack is an accordion stack.
 16. The assembly of claim 12 wherein theseatbelt webbing is a chest strap in a three-point vehicle occupantseatbelt.
 17. The assembly of claim 11 wherein top and bottom strips ofthe inflatable bag are stitched together to form a sleeve for theremaining strips and the sleeve is external to the webbing.
 18. A methodof packing an automotive airbag comprising: welding a plurality ofmaterial strips into an inflatable bag such that, at weld joints betweenthe plurality of strips, a first strip lays flat on top of a secondstrip; stacking the strips in a stack; and securing the bag to aseatbelt webbing.
 19. The method of claim 18 wherein the welding is edgejoint welding.
 20. The method of claim 18 wherein the stack is anaccordion stack.